Little Snape and a raven

Before Severus met Lily, he used to wander alone in the forests, practicing magic and collecting stuff. In my imagination, he one day saved a little raven who's mother had died and took care of the little one. The raven followed him everywhere, even to Hogwarts, and it became Severus's Familiar. The bird didn't live in the owlery with the Owl's, but in forbidden forest, from where it came flying when Severus called him.